I have next problem at booting gentoo:
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(8,3)

I've read about this problem, and many ppl suggests that it is filesystem problem.

sda3 is formatted in ext4.

But I have some disturbing information about my system from different programs:
- When I setted up lilo, It wrote Warning: "partition type 0xAF on device 0x803 is a dangerous place for a boot sector"
0XAF it looks like a HFS/HFS+ filesystem, which is normally mac uses.

- Disk utility in mac recognizes sda3 as HFS/HFS+ too.
- also in linux fdisk -l says that it's a HFS/HFS+ filesystem
- Windows recognizes this disk but it cannot define the filesystem, but it can read sda2 partition, which is rly HFS+

- But other programms like a linux command 'df -T' writes that sda3 has ext4 (which it should be, because before installing gentoo I had formatted it with mkfs.ext4)

I'm sorry for my bad English.
And I'm asking you for a help
Thank you

P.S. I actually can boot my gentoo system with bootloader from disc sysreccd. But with standart kernel (3.4.30-std340-amd64).

I don't know much about diskutil, if I were you I'd try to change the type of the partition with fdisk, not entirely sure whether this will fix your problem though, but it is the first thing that appears to be wrong. Back up your data first, of course